Attachment 3B - Process Design Strategy - OREZ · 132005.638.06

PR25001 Noosa Composting Facility
Process Design Strategy




floor, typically through a sloped floor or integrated drainage channels running the length of
the tunnel. Because the tunnel is a sealed structure, this leachate is fully contained within the
vessel rather than able to run off into the surrounding site, which is a further point of
environmental control IVC offers relative to open composting methods where run-off must
instead be managed through site-wide stormwater infrastructure.

Collected leachate is returned to the process wherever it can be usefully absorbed, which
recovers moisture and nutrients that would otherwise be lost and reduces the volume
requiring separate management. Moisture control into the tunnels is achieved principally by
adding leachate at the drop point of the intermediate bunker feed conveyor, where the FO
and shredded GO are mixed prior to tunnel filling, so that the blend reaches the target inlet
moisture content before loading. Leachate may also be sprayed onto the pile within the
tunnel where further moisture addition is required during the retention period.

Where leachate volumes exceed what can be usefully returned to the process, for example
during high moisture ramp-up periods or where wetter feedstock streams are introduced, the
surplus requires a dedicated storage and treatment pathway.


2.4.     Refining
On completion of the tunnel cycle, material is transferred from the IVC tunnel to a stationary
drum screen with a feed hopper. The screen splits the material at a 15 mm aperture into a
fines fraction (<15 mm) and an oversize fraction (>15 mm), each conveyed into its own
bunker. The oversize material passes under a vacuum hood located above the drop point in
the bunker, capturing light material such as film plastics to reduce oversize contamination.
The fines fraction is then transferred via a front-end loader to one of eight dedicated
maturation storage bays for the six-week maturation period, the fines are typically turned into
an available bunker weekly or fortnightly to aerate the pile and aide with maturation. The
oversize material is transferred by a front-end loader to one of two dedicated maturation
storage bays prior to offsite dispatch.

Space has been allocated on the eastern side of the maturation building for future
maturation bay expansion, where a crushed concrete slab is being considered to provide
further oversize storage prior to implementing a maturation building extension. This will be
confirmed during detailed design.

2.4.1.   Oversize Fraction Recovery Options

The current basis of design produces a single oversize fraction at the 15 mm screen cut. NSC
has asked whether two oversize fractions of differing particle size could be produced to
increase product recovery and marketability from the oversize stream.

This is an opportunity to be evaluated rather than a change to the basis of design. The single
15 mm cut remains the baseline, and the palm content in the feedstock means the oversize
tonnage may be larger than modelled, which strengthens the case.

Three options are available within the nominated process train:




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